Field of the Invention
This invention relates to a self-sealing fastener, and in particular, a self-sealing furring nail.
In the building industry, sealing out water, which can cause many problems, is always desirable. In fact, making structures watertight against rainwater, irrigation water, and any other moisture is a primary concern. Unfortunately, the materials which work well as an exterior coating, such as plaster and stucco (hereinafter, "stucco"), do not provide a watertight seal. The stucco exterior is breathable by design, so that it will air-out and dry naturally. Otherwise, entrapped water would mold, mildew or create freezing and thawing, or other problems associated with waterproof exterior systems. Therefore, the stucco can become saturated from rainwater, and may also have leaks due to cracking. The water seal is actually provided by building paper, which is typically a black paper wrapped around and stapled to the framing of a home or other structure.
When the exterior stucco becomes saturated during a rainstorm, water works its way through the stucco to the building paper. The water then flows downward and out the bottom of the stucco wall. The remaining moisture in the stucco will air out.
As can be seen from above, it is important, particularly during construction, to maintain the integrity of the building paper. Most competent builders and contractors are aware that leaks can occur through the building paper and attempt to seal certain large penetration holes, such as at electrical outlets, gas and water pipes and other large penetrations. Typically, a sealant is applied with a caulking gun. However, little attention is paid to the most numerous form of penetration hole in the building paper. That is, the furring nails which are used to support lath wire on which the stucco is applied.
In a typical residence, the nails are six inches (6") apart vertically and three inches (3") apart around the perimeter, so there may be twenty-five to thirty thousand or more furring nails. Every one of these nails creates a potential penetration point for water. Though small, these holes can often leak. Moreover, due to movement of the building paper during construction, the holes can become enlarged or torn. Because caulking all these penetration holes would be very labor intensive, and because not all of these holes leak, they are ignored.
Understanding the construction of a stucco exterior aids in understanding why caulking is impractical. After the building frame is completed, building paper is wrapped around it, or around plywood reinforcing if such reinforcing is used, and stapled to the framing. Then the lath wire is positioned around the building paper and held in place by the furring nails. The nails not only hold the building paper on the framing but also support the lath wire. The nails have what is known as a furring wad on them. The wad essentially serves to space the lath wire from the building paper and typically is made out of cardboard. Once the nails are in place, the stucco is applied as is well known in the art.
As noted above, although one of the most common entry points for water is through holes created by furring nails, this is ignored. Yet, if water intrusion occurs, it is extremely difficult and expensive to attempt repairs. The homeowner or building owner will have to either "live with the problem," or endure repair. The repair would involve first opening up the exterior stucco to the building paper. Even if this can be done without damaging the paper, the repair next involves caulking each penetration hole from the furring nails in the section where the leak is occurring, then putting up new lath wire and new stucco. This will probably necessitate using new furring nails and further caulking those new nails.
Furring nails and stucco construction have been used for a very long time. For example, U.S. Pat. No. 1,767,565 issued Jun. 24, 1930 to M. B. Thrift et al. discloses a furring device, in particular for metallic glass. The nail has a stop for a spacer which is resilient. The spacer spaces glass from a sheet and the nail goes into the studs. The resilient spacer is thus an attempt to provide a seal. However, this furring nail is not used for building paper and lath wire. Moreover, a resilient member will not ensure a seal, particularly if the penetration hole has been enlarged by tearing or rubbing.